“You can tell if learning is taking place if the kids are having a good time and are curious about what’s going on,” Paradis said. “Having fun does not mean there is no learning taking place; it’s like reading a good novel where you can’t wait to turn the page.”

For 42 years, Paradis has brought his particular brand of physics teaching to Fort Kent Community High School. He tried to retire in 2005, but within months SAD 27 requested he come back part time.

Friday, Paradis, a sort of cross between Bill Nye the Science Guy and Mr. Wizard, takes his physics show on the road to present his Aroostook County Potato Gun Lab at the annual Maine Physics Teachers’ meeting hosted by the University of Maine in Orono.

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“I started doing this 20 years ago,” Paradis said as he assembled the “gun” in his high school lab Monday afternoon. “It’s a real attention-getter.”

Using a section of 32-inch pipe he specially cut and flanged, a wooden dowel and slice of potato — he claims Aroostook County potatoes add a certain “je n’sais quois” — Paradis forces a section of potato into the pipe.

He then pushes a second piece of potato into the pipe and the subsequent compressing of air fires the first slice out of the pipe “at subsonic speed” and creates an audible POP.

“This tends to get the attention of even the most bored of your students,” Paradis said.

The experiment, he said, challenges the students to use physics knowledge to calculate the speed of the potato bullet.

“Physics is fun,” Paradis said. “It’s the reason I’m still teaching. If I found it was not fun, I would not be as effective a teacher.”

Not a big fan of lecturing in front of students for large blocks of time, Paradis spends a small part of his class time lecturing and the rest of the period interacting with the students using something called “lecture feedback.”

Paradis will pose a question to the class and then poll them on which of several answers he offers is correct.

Teacher and students then discuss each answer, why some students felt it was right or wrong, and eventually all agree on the correct answer.

“I’ve found a way to engage the students and get them involved,” he said. “I keep asking questions until they come up with the correct answer.”

On Monday afternoon, two of his students were in his lab working on an experiment calculating the relationship between mass and acceleration. Stepping up to view their results on the computer, Paradis was an enthusiastic cheerleader.

“That’s some good data in there,” he told them.

“He really does make it fun,” Carter Vaillancourt, a senior at community high school, said. “He matches it with real-life situations.”

Lab partner and fellow senior Tim Voisine agreed. “He shows us how it applies in life,” Voisine said. “We don’t just sit and listen [and] when you leave his classroom you think of everything out there on a whole new level.”

The two students pointed to the acceleration experiment as an example.

“It’s showing us how force affects things in real life,” he said.

“We talk about how friction and mass work when driving on snow,” Paradis said. “When you add more mass to something — like putting weight in the back of your car — it gives you better traction.”

Paradis pointed to the computers the two students were using, noting how technology has changed the science.

“Computers make it much more efficient and fun by taking the drudgery out of the calculations,” he said. “The experiment they are working on takes 20 minutes on the computer and those calculations would have taken two hours without one.”

Over the students’ heads, a giant model of a working slide rule, something Paradis uses to demonstrate how physics’ calculations were done decades ago, hangs on the lab’s wall.

Along with computers, Paradis also uses stories to bring the science of physics to life.

Take the potato gun.

According to Paradis, the design dates back to 19th century England where citizens were not allowed to carry firearms.

Older gentlemen walking home late at night from the pub made easy targets for robbers so they devised a “gun” using a hollowed out cane and the same principles applied by Paradis in the potato gun.

“They would point the cane-gun at a would-be attacker and fire a lead pellet,” Paradis said. “The word got around fast to stay away from anyone carrying a cane.”

Over the years Paradis’ style and classes have proved popular with the students at community high school with at times 60 out of 100 seniors signed up for his physics courses.

At 65, Paradis said he has no thoughts of completely retiring from the classroom any time soon.

“Not as long as I’m healthy and the kids are liking it,” he said. “If the kids are not turned on by it, I would not want to come in.”

Still, there are some things Paradis wants to accomplish outside the classroom someday.

Already a passionate carpenter, the former coach of the high school Nordic ski team — he’s part of several volunteer ski groups and boards of directors in Fort Kent — Paradis would like to compete in the American Birkebeiner Nordic ski marathon in Wisconsin.

He also would like to learn how to make pottery and how to play the piano.

“Of course, the piano could be a problem,” he said. “I’m a little tone deaf.”